This apparatus consists of two generators, one at each end, and three stationary fountains, all made of copper, the generator lead-lined, the fountains tin-lined. The purifiers are adjusted at the sides of the generators.

The agitators are furnished with wheel cranks to use by hand power, and also to start the agitators before shifting the belt to put on the power.

Fig. 175. - Safety Valve.

On the rear, and out of the way of the operator, is attached a wide pulley, so that the power can be used from a counter-shaft above.

On the generator is placed a gas bell, into which the gas rises, and to which the pipes and safety valve are attached. This will prevent the clogging of the pipes by the foaming of the carbonate. The acid valve is raised and locked by a wheel and screw placed conveniently for the operator.

The safety valve consists of a weighted ball and hinged lever pressing a rubber washer on a metal bearing, having a direct inlet to body of genera-tor. It works automatically at a set pressure, and allows the gas to be blown off at any pressure by simply raising the ball with the hand, enabling the operator to test the working of the valve at any stage of the operation.

Fig. 176. - Blow-off Cock.

Fig. 177. - Pressure Gauge.

The blow-off cock allows the contents of the generator to be drawn off gradually. A pressure gauge is attached to purifier on either side.